wxGUI/rlisetup manual: sampling scheme quality manually improved from jpg original

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@64626 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/rlisetup/g.gui.rlisetup.html

@@ -34,7 +34,7 @@ Definition of creation of sampling area:
 -->
 </ul>
 
-<img src="g_gui_rlisetup_sampleAreas.jpg" alt="Sampling area definitions">
+<img src="g_gui_rlisetup_sampleAreas.png" alt="Sampling area definitions">
 
 <p>
 Definition of region for analysis: